// JavaScript Document

(function($) {
   if(!document.defaultView || !document.defaultView.getComputedStyle){
       var oldcss = jQuery.css;
       jQuery.css = function(elem, name, force){
           if(name === 'background-position'){
               name = 'backgroundPosition';
           }
           if(name !== 'backgroundPosition' || !elem.currentStyle || elem.currentStyle[ name ]){
               return oldcss.apply(this, arguments);
           }
           var style = elem.style;
           if ( !force && style && style[ name ] ){
               return style[ name ];
           }
           return oldcss(elem, 'backgroundPositionX', force) +' '+ oldcss(elem, 'backgroundPositionY', force);
       };
   }

   var oldAnim = $.fn.animate;
   $.fn.animate = function(prop){
       if('background-position' in prop){
           prop.backgroundPosition = prop['background-position'];
           delete prop['background-position'];
       }
       if('backgroundPosition' in prop){
           prop.backgroundPosition = '('+ prop.backgroundPosition + ')';
       }
       return oldAnim.apply(this, arguments);
   };

   function toArray(strg){
       strg = strg.replace(/left|top/g,'0px');
       strg = strg.replace(/right|bottom/g,'100%');
       strg = strg.replace(/([0-9\.]+)(\s|\)|$)/g,"$1px$2");
       var res = strg.match(/(-?[0-9\.]+)(px|\%|em|pt)\s(-?[0-9\.]+)(px|\%|em|pt)/);
       return [parseFloat(res[1],10),res[2],parseFloat(res[3],10),res[4]];
   }

   $.fx.step.backgroundPosition = function(fx) {
       if (!fx.bgPosReady) {
           var start = $.css(fx.elem,'backgroundPosition');

           if(!start){//FF2 no inline-style fallback
               start = '0px 0px';
           }

           start = toArray(start);

           fx.start = [start[0],start[2]];

           var end = toArray(fx.end);
           fx.end = [end[0],end[2]];

           fx.unit = [end[1],end[3]];
           fx.bgPosReady = true;
       }

       var nowPosX = [];
       nowPosX[0] = ((fx.end[0] - fx.start[0]) * fx.pos) + fx.start[0] + fx.unit[0];
       nowPosX[1] = ((fx.end[1] - fx.start[1]) * fx.pos) + fx.start[1] + fx.unit[1];
       fx.elem.style.backgroundPosition = nowPosX[0]+' '+nowPosX[1];
   };
})(jQuery);